<%--
  Created by IntelliJ IDEA.
  User: Lenovo
  Date: 2021/7/31
  Time: 14:08
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html>
<!-- head -->
<head>
    <meta charset="utf-8">
    <title>图片登录验证</title>
    <meta name="renderer" content="webkit">
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
    <link rel="stylesheet" href="https://www.layuicdn.com/layui-v2.6.8/css/layui.css"  media="all">
    <style>
        body{margin: 10px;}
        .demo-carousel{height: 200px; line-height: 200px; text-align: center;}
        .code {
            width: 400px;
            margin-top: 18%;
            margin-left: 35%;
        }
        .input-val {
            width: 295px;
            background: #ffffff;
            height: 2.8rem;
            padding: 0 2%;
            border-radius: 5px;
            border: none;
            border: 1px solid rgba(0,0,0,.2);
            font-size: 1.0625rem;
        }
        #canvas {
            float: right;
            display: inline-block;
            border: 1px solid #ccc;
            border-radius: 5px;
            cursor: pointer;
        }
        .btn {
            width: 100px;
            height: 40px;
            background: #00aa00;
            border: 1px solid #ccc;
            border-radius: 5px;
            margin: 20px auto 0;
            display: block;
            font-size: 1.2rem;
            color: #ffffff;
            cursor: pointer;
        }
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

    </style>
</head>

<script src="http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script>
<body cz-shortcut-listen="true" class="layui-layout-body">

<div class="layui-layer-move">
    <div class="code">
        <input type="text" value="" placeholder="请输入验证码（不区分大小写）" class="input-val" >
        <canvas id="canvas" width="100" height="43" ></canvas>
        <button class="btn" >提交</button>
    </div>

</div>
</body>
<script>

    $(function(){
        var show_num = [];
        draw(show_num);

        $("#canvas").on('click',function(){
            draw(show_num);
        })
        $(".btn").on('click',function(){
            var val = $(".input-val").val().toLowerCase();
            var num = show_num.join("");
            if(val==''){
                alert('请输入验证码！');

            }else if(val == num){
                var msg = confirm("验证成功");
                if (msg) {
                    window.location.href = "Menu";
                }
                $(".input-val").val('');
                draw(show_num);

            }else{
                alert('验证码错误！请重新输入！');
                $(".input-val").val('');
                draw(show_num);
            }
        })
    })

    function draw(show_num) {
        var canvas_width=$('#canvas').width();
        var canvas_height=$('#canvas').height();
        var canvas = document.getElementById("canvas");//获取到canvas的对象，演员
        var context = canvas.getContext("2d");//获取到canvas画图的环境，演员表演的舞台
        canvas.width = canvas_width;
        canvas.height = canvas_height;
        var sCode = "A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0";
        var aCode = sCode.split(",");
        var aLength = aCode.length;//获取到数组的长度

        for (var i = 0; i <= 3; i++) {
            var j = Math.floor(Math.random() * aLength);//获取到随机的索引值
            var deg = Math.random() * 30 * Math.PI / 180;//产生0~30之间的随机弧度
            var txt = aCode[j];//得到随机的一个内容
            show_num[i] = txt.toLowerCase();
            var x = 10 + i * 20;//文字在canvas上的x坐标
            var y = 20 + Math.random() * 8;//文字在canvas上的y坐标
            context.font = "bold 23px 微软雅黑";

            context.translate(x, y);
            context.rotate(deg);

            context.fillStyle = randomColor();
            context.fillText(txt, 0, 0);

            context.rotate(-deg);
            context.translate(-x, -y);
        }
        for (var i = 0; i <= 5; i++) { //验证码上显示线条
            context.strokeStyle = randomColor();
            context.beginPath();
            context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height);
            context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height);
            context.stroke();
        }
        for (var i = 0; i <= 30; i++) { //验证码上显示小点
            context.strokeStyle = randomColor();
            context.beginPath();
            var x = Math.random() * canvas_width;
            var y = Math.random() * canvas_height;
            context.moveTo(x, y);
            context.lineTo(x + 1, y + 1);
            context.stroke();
        }
    }

    function randomColor() {//得到随机的颜色值
        var r = Math.floor(Math.random() * 256);
        var g = Math.floor(Math.random() * 256);
        var b = Math.floor(Math.random() * 256);
        return "rgb(" + r + "," + g + "," + b + ")";
    }
</script>
</html>
